The technical development of shoes, in particular sports shoes, has advanced in recent years. Presently, sophisticated cushioning systems are available, which accommodate varying requirements during a gait cycle and which selectively support the biomechanical processes occurring during walking or running. Use of plastic materials in the manufacture of sports shoes is directly responsible for these improvements in cushioning and support.
Incorporation of plastics into footwear, however, has reduced the permeability for air and moisture that was available with more natural footwear materials, such as leather and fabric. It is well-known that the foot has a particularly high density of perspiration pores, which release great amounts of moisture, especially during sports activities. This excessive moisture should be quickly removed from the surface of the foot in order to avoid a humid foot climate, a condition that at a minimum causes discomfort and odor, but at worst, may lead to foot diseases. Thus, it is desirable that there be sufficient ventilation of the interior of the shoe and, thereby of the foot. For this reason, different approaches to ventilate and remove sweat from the foot area exist in the art.
For example, one Applicant of the present invention has also disclosed, in German Patent No. DE 100 36 100, the disclosure of which is hereby incorporated herein by reference in its entirety, a multilayer sole construction having overlapping openings in different sole layers in order to ventilate the interior of the shoe from below. German Patent No. DE 100 36 100 is the foreign counterpart to U.S. patent application Ser. No. 09/915,216, Publication No. 02-0017036, the disclosure of which is hereby incorporated herein by reference in its entirety.
Other types of shoes can be more easily ventilated, because of their specific use. U.S. Pat. No. 4,640,027, the disclosure of which is hereby incorporated herein by reference in its entirety, discloses a motor cycling boot wherein the passing airflow is guided into the interior of the shoe via an opening arranged in the boot shaft. U.S. Pat. No. 6,196,556, the disclosure of which is hereby incorporated herein by reference in its entirety, teaches a similar arrangement in an inline roller skate where airflow is directed through an opening at the front end of the shoe, thereby ventilating the foot via several holes in the sole of the skate. In both examples, the high relative velocity of the shoe during use aids in guiding the air into the interior of the shoe; however, these constructions transferred to ordinary shoes produce less than desirable results, and a considerably reduced ventilation effect is noted. This result clearly indicates that the arrangement of openings in the shoe alone generally is not sufficient for effective ventilation.
There is, therefore, a need for a shoe ventilation system that facilitates airflow within the shoe, even at the low relative velocities typical of walking or running.